Subject: [EAPEXT] How does eap-sim authentication start from authenticator sending "Identity request" message?

From: mandar naik <[email-masked]>
Date: Tue, 24 Jan 2012 19:07:25 +0530 (IST)

Hi,
 I was trying to learn EAP-SIM authentication and I have gone through RFC 4186 which talks about the same.
As per RFC, authentication process starts with" Identity request"from authenticatorbut I had a question that 

how authenticator gets an indication to initiate EAP-SIM process by sending "Identity request"? 

Could anyone explain more about this scenario ?
Thanking in anticipation,

Best Regards, 

Mandar Naik